An injection-moulding apparatus of the type defined in the opening sentence is known from U.S. Pat. No. 4,185,955. The second mould section of said apparatus comprises the means for moving the punch. These means comprise a pneumatic cylinder in which piston is arranged to reciprocate a plate to which the punch has been secured. This cylinder is connected to a pneumatic control system via lines. If by means of this injection-moulding apparatus a product is to be manufactured which differs from the previously manufactured product the second mould section must be converted. For this purpose the mould section has to be removed from the injection-moulding apparatus in view of the space necessary for conversion. With the prior-art injection-moulding apparatus this is laborious and time-consuming because it is also necessary to disconnect pneumatic supply and discharge lines and because auxiliary devices, for example a hoist, have to be used since the mould section is heavy. This is an expensive operation because production is held up during the conversion. Since manufacturers wish to minimize stocks and wish to offer products in small series, the demand for small batches of a product increases. This leads to an increased conversion time in proportion to the production time, resulting in a rise of the product costs.